It is widely known that powdered polytetrafluoroethylene polymer can act as a thickening agent for a liquid lubricant, such as a perfluoropolyether or fluorosilicone, to produce a lubricant having a grease consistency. Such grease compositions exhibits relatively good lubricating properties for bearings operating at high load and low speed. However, under certain extreme pressure conditions, which also require the bearing to operate at high speeds and high temperatures, use of this type of grease often results in relatively short bearing life. Such heavy duty service is typically experienced, for example, by bearings in conveyor chain used in the manufacture of metals and electric bulbs and in machinery used in the production of coiled metal, textiles and paper. Therefore, these applications provide continuing motivation for those skilled in the art to develop grease formulations which offer improved load resistance, thermal resistance, resistance to wear, low friction and a wide temperature range of application.